Two-piece high-strength screw

Abstract

High-strength screw (1), with a head (2) with a tool engagement contour (4), a shank (3) with a free end (5) pointing away from the head (2), a threaded section (6) with a thread (7) being arranged on the shank (3), the thread (7) being formed as a metric ISO thread or inch thread, the head (2) and the shank (3) being designed as materially separate parts, the head (2) having a coupling recess (8) arranged radially inside with an axial force transmission element (9) and a torque transmission element (10), the shank (3) having a coupling element (11) arranged radially outside on its outer circumference with an axial force transmission counter element (12) and a torque transmission counter element (13), the coupling element (11) engaging in the coupling recess (8), the axial force transmission element (9) and the axial force transmission counter element (12) being designed and arranged to positively interlock in such a way that an axial translatory movement of the head (2) relative to the shank (3) in the direction away from the free end (5) of the shank (3) is prevented or will be prevented, in particular non-releasably, and the torque transmission element (10) and the torque transmission counter element (13) being designed and arranged to interlock in such a way that a rotational movement of the head (2) relative to the shank (3) in the tightening direction of the thread (7) is or will be prevented.

1 . A high-strength screw ( 1 ), with
 a head ( 2 ) with a tool engagement contour ( 4 ),   a shank ( 3 ) with a free end ( 5 ) pointing away from the head ( 2 ),   wherein a threaded section ( 6 ) with a thread ( 7 ) is arranged on the shank ( 3 ),   wherein the thread ( 7 ) is formed as a metric ISO thread or inch thread,   wherein the head ( 2 ) and the shank ( 3 ) are formed as materially separate parts,   wherein the head ( 2 ) has a coupling recess ( 8 ) arranged radially inside with an axial force transmission element ( 9 ) and a torque transmission element ( 10 ),   wherein the shank ( 3 ) has a coupling element ( 11 ) arranged radially outside on its outer circumference with an axial force transmission counter element ( 12 ) and a torque transmission counter element ( 13 ),   wherein the coupling element ( 11 ) engages in the coupling recess ( 8 ),   wherein the axial force transmission element ( 9 ) and the axial force transmission counter element ( 12 ) are designed and arranged to positively interlock in such a way that an axial translatory movement of the head ( 2 ) relative to the shank ( 3 ) in the direction away from the free end ( 5 ) of the shank ( 3 ) is prevented or will be prevented, in particular non-releasably, and   wherein the torque transmission element ( 10 ) and the torque transmission counter element ( 13 ) are designed and arranged to interlock in such a way that a rotational movement of the head ( 2 ) relative to the shank ( 3 ) in the tightening direction of the thread ( 7 ) is or will be frictionally prevented.   
     
     
         2 . The high-strength screw ( 1 ) according to  claim 1 , wherein the coupling recess ( 8 ) is stepped and has a first portion ( 14 ) with a first inner diameter ( 15 ) and a second portion ( 16 ) with a second inner diameter ( 17 ), the first inner diameter ( 15 ) being larger than the second inner diameter ( 17 ), and
 wherein the second portion ( 16 ) is located closer to the free end ( 5 ) of the shank ( 3 ) than the first portion ( 14 ).   
     
     
         3 . The high-strength screw ( 1 ) according to  claim 2 , wherein the second portion ( 14 ) forms the axial force transmission element ( 9 ) in the sense of an axial stop. 
     
     
         4 . The high-strength screw ( 1 ) according to  claim 3 , wherein the coupling element ( 11 ) forms an axial counter stop corresponding to the axial stop, the outer diameter of which is greater than the outer diameter of the shank ( 3 ) and greater than the second inner diameter ( 17 ) of the coupling recess ( 8 ). 
     
     
         5 . The high-strength screw ( 1 ) according to  claim 2 , wherein the first portion ( 14 ) forms the torque transmission element ( 10 ). 
     
     
         6 . The high-strength screw ( 1 ) according to  claim 2 , wherein the second portion ( 16 ) forms the torque transmission element ( 10 ). 
     
     
         7 . The high-strength screw ( 1 ) according to  claim 1 , wherein the torque transmission element ( 10 ) and the torque transmission counter element ( 13 ) are designed and arranged to positively interlock. 
     
     
         8 . The high-strength screw ( 1 ) according to  claim 1 , wherein the torque transmission element ( 10 ) and the torque transmission counter element ( 13 ) belong to the geometry type polygon, multi-tooth, multi-round or star. 
     
     
         9 . The high-strength screw ( 1 ) according to  claim 1 , wherein the torque transmission element ( 10 ) and the torque transmission counter element ( 13 ) are designed and arranged to interlock in such a way that a rotational movement of the head ( 2 ) relative to the shank ( 3 ) in the direction of loosening rotation of the thread ( 7 ) is also prevented. 
     
     
         10 . The high-strength screw ( 1 ) according to  claim 1 , wherein the torque transmission element ( 10 ) and the torque transmission counter element ( 13 ) are each formed symmetrically in the circumferential direction. 
     
     
         11 . The high-strength screw ( 1 ) according to  claim 1 , wherein the torque transmission element ( 10 ) and the torque transmission counter element ( 13 ) are each formed asymmetrically in the circumferential direction. 
     
     
         12 . The high-strength screw ( 1 ) according to  claim 11 , wherein the torque transmission element ( 10 ) and the torque transmission counter element ( 13 ) are formed and arranged in such a way that a rotational movement of the head ( 2 ) relative to the shank ( 3 ) in the loosening direction of the thread ( 7 ) is not or will not be prevented. 
     
     
         13 . The high-strength screw ( 1 ) according to  claim 1 , wherein the torque transmission element ( 10 ) and the torque transmission counter element ( 13 ) are formed in such a way that they determine the maximum tightening torque of the screw ( 1 ) and, if the maximum tightening torque is exceeded, no longer prevent the rotational movement of the head ( 2 ) relative to the shank ( 3 ) in the tightening direction of the thread ( 7 ). 
     
     
         14 . The high-strength screw ( 1 ) according to  claim 1 , wherein the shank ( 3 ) consists of high-strength steel or a fibre composite material, and the head ( 2 ) consists of high-strength steel or a fibre composite material. 
     
     
         15 . A forming method for the mechanical production of a high-strength screw ( 1 ) according to at least one of the preceding claims, from a head blank and a shank blank ( 19 ), comprising the steps:
 forming the head blank in a forming tool in such a way that a head ( 2 ) of a screw ( 1 ) with a coupling recess ( 8 ) arranged radially inside with an axial force transmission element ( 9 ) and a torque transmission element ( 10 ) is produced,   threading the head ( 2 ) by means of the coupling recess ( 8 ) onto a shank blank ( 19 ),   forming a part of the shank blank ( 19 ) in a forming tool in such a way that a shank ( 3 ) with a coupling element ( 11 ) arranged radially outside on its outer circumference with an axial force transmission counter element ( 12 ) and a torque transmission counter element ( 13 ) is produced, and   joining of head ( 2 ) and shank ( 3 ) by translatory displacement of the head ( 2 ) in such a way that the coupling element ( 11 ) engages in the coupling recess ( 8 ).   
     
     
         16 . The forming method according to  claim 15 , further characterized by the following steps:
 before the threading step: forming the head blank in a forming tool in such a way that a tool engagement contour ( 4 ) is produced, and/or   after the joining step: securing the head ( 2 ) to the shank ( 3 ) to prevent axial translational movement of the head ( 2 ) relative to the shank ( 3 ) in the direction of the free end ( 5 ) of the shank ( 3 ), and/or   wherein the forming is in each case cold forming, and/or   wherein the forming of the part of the shank blank ( 19 ) takes place by means of a translatory moved punch ( 21 ), and/or   wherein the shank blank ( 19 ) is held by clamping jaws ( 20 ) during forming.